Compressor control device



@111 21, 1936. I J, Q'MCCU E 2,038,184

COMPRES SOR CONTROL DEVICE Filed Jan. 11, 1954 POWER ON POWER OFF 'INVENTOR JOSEPH C. McCUNE A TTORNE Patented Apr. 21, 1936 UNITED! STATES PATENT F CE.

Application January 11, 1934, Serial No. 706,228

13 Claims.

This'invention relates to apparatus employed on electric traction vehicles for compressing fluid for use in controlling the fluid pressure'brakes.

On vehicles equipped with a fluid compressor, a governor device is provided which is adapted, upon a predetermined reduction in pressurev in the main or storage reservoir, to effect the starting of the compressor. When the compressor is thus started, it continues to, operate at a substantially constant speed until the main reservoir pressure has been increased to a predetermined maximum degree, at which time the governor operates to efiect the stopping of the compressor. The running of the. compressor is apt to be noisy to such anfextent as to be disagreeable and annoying, especially when the vehicle is standing.

The principal object of this invention is to re-. duce the operating noise of the compressor by providing automatic means for causing the compressor to run at a low speed when the vehicle is being propelled, which speed is sufficiently fast to normally insure an adequate supply of fluid under pressure for controlling the fluid pressure brakes, and for preventing the compressor from operating while the vehicle is standing, or unless the main reservoir pressure has been reduced to a very low degree, at which time the compressor will run at full speed, so as to quickly charge the storage reservoir.

:In the accompanying drawing, the single figur is a diagrammatic view of a control system, embodying my invention, for a motor of a fluid compressor.

As shown in the drawing, the control system may comprise a fluid compressor I adapted to be driven by an electric motor 2 and adapted to compress fluid through a pipe 3 into a main or storage reservoir 4, a normal compressor governor device 5 and an additional compressor governor device 6.

The normalgovernor device 5 is shown diagrammatically as comprising a casing containing a piston I, subject on one side to the pressureof fluid as supplied from the main reservoir -4 through pipes 8 and 9, subject on the opposite side to the pressure of a-spring I0. The piston! carries a stem II having secured thereto a contact member I2 which is operable by the piston to control a circuit leading to the compressor motor 2. Said contact member is adapted, when the piston is'in its inner position, to close a circuit :leading to'the compressor motor and to open thecircuit when the piston is moved outwardly.

The governor device 6 comprises a piston I3 subject on one side to the pressure of fluid as supplied from the main reservoir 4 through pipe 8, and subject on the other side to the pressure of a spring I4. The piston I3 is provided with a stem I5 carrying the contact members I6 and II which are operable by the piston to also control circuits leading to the compressor motor 2. The contact: member I ,6. isadapted, when the piston is in its outer position, to closethe circuit to the compressor motor which circuit, includes the contact member I2; and to open said circuit and close another circuit tothecompressor motorindependent of the contact member I2 when thepis ton is inits inner position.

'Ifheecontactmember. I2 is associated with fixed contacts I8 and I9, the contact I 8, being connected to wire 20: leadingto the; compressor motor 2 and contact I9 being connected by wire 21' to a fixed contact 22 associated with the contact member It. The other contact 23 associated with the contact member I6 is connected by wire 24 to wire 25, which wire 25 connects the car motor 21' in series with the car motor 26. The contacts 28 and 29 are adapted to be engaged by the contact member H, the contact 28 being connected by wire, 30. to wire 20 and the contact 29 being connected to the trolley wire 3| by wire '32.

In operation, assume that the governor device 5 is adjusted for controlling the compressor motor 2 within the usual maximum and minimum pressure range as ordinarily employed and that the governor device 6 is adjusted so that the'piston will not move to its inner position until the pressure in the main reservoir 4 has been'reduced to a relatively low degree, which is considerably lower than the pressure at which the governor device 5 operates to cut in the compressor motor but which is sufiicient to insure ample main re'servoir pressure for operating the brakes to hold the car while standing.

. -With the usual power controller drum 33 in a power on position, the contact 34 on the controller drum 33 closes a circuit from the trolley wire 3I to the car motors 26 and 21, which circuit includes the wire 32, wire 35,'contact 34, wire 36 and wire 25. Thus current is supplied to the car motors :for propelling the car. It will be understood that the icontroller is "shown diagrammatically and for the purpose of illustration is shown as having only one power on position, in which position one electric circuit is established forcontrollingthe car motors whereas, in reality, the usual controller is provided with a plurality of power on positions :for controlling the car motor circuits.

With the wire 25 thus energized and the switch piston vI3 :in its outerposition so that the contact member I6 connectsthe contacts 23 and 22, the governor device 5 controls the supply of current to.the compressor motor 2. With the pressure of the fluid in the .main reservoir 4 lower than the cutting-out pressure of the governor, the piston I is in its inner position, as shown inthe. drawing, so that the contact member .12 closes a vcircuitfromthe wire 25 to the compressor motor 2 through wire 24, contacts 23 and 22, contact member l6, wire 2|, contacts l9 and I8, contact member 12 and wire 20. Due to the drop in voltage across the car motor 26, the voltage of the current supplied to wire 25, and thereby to the compressor motor, is considerably reduced, with the result that the compressor motor runs at a low speed.

If the car is to be brought to a stop, the power controller drum is shifted to off position, thereby causing the contact 34 to break the connection from wire to wire 36 and thereby open the circuit to the car motors 26 and 21 and consequently the above mentioned circuit to the compressor motor.

When the pressure in the main reservoir 4 has been reduced to a predetermined low degree, the piston l3 in the governor device 6 will move to its inner position so as to cause the contact member IT to engage the contacts 28 and 29. A circuit is thus established from the trolley wire 3| to the compressor motor 2 through wire 32, contacts 29 and 28, the contact member I! and wires 36 and 20. Thus, current at full voltage is supplied to the compressor motor, with the result that said motor will run at full speed and quickly charge the main reservoir.

It will be noted that the movement of the piston 13 to its inner position causes the contact member I6 to be moved out of engagement with the contacts 22 and 23. If said contact member were not moved out of engagement with said contacts and the contact members l1 and I2 were in their circuit closing positions, then current supplied to wire 20, as above mentioned, would flow to the car motor 21 through contacts l8 and I9, contact member l2, wire 2|, contacts 22 and 23, contact member l6, and wires 24 and 25, thereby causing unintended operation of said car motor. With the contact member l6 out of engagement with the contacts 22 and 23, however, this flow of current is prevented.

It will be seen from the foregoing that when the power controller is in power on position for causing the car to be propelled, current at less than full voltage is adapted tobe supplied to the compressor motor, the circuit to said motor being controlled at this time by the normal governor device so as to maintain the pressure in the main reservoir within the pressure range of said governor, and when supplied with this low voltage current, the compressor will run at low speed. It will further be seen that when the car is standing, the compressor remains idle, unless the main reservoir pressure should fall to the low degree at which the low pressure governor device is adjusted to operate, and when said governor device operates, it closes a circuit through which current at full voltage is supplied to the compressormotor, with the result that said motor then operates at full speed so as to quickly charge the main reservoir.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the terms of the appended claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. The combination with a plurality of series connected electric motors, a power controller for said motors having power on and power oil positions, a fluid compressor and an electric motor for actuating said compressor, of means operative in a power on position of said controller to connect said actuating motor to the circuit including said series connected motors at a point intermediate two of said motors for supplying current at one voltage to said actuating motor, and means operated upon a fall in the pressure of the fluid compressed by said compressor to a predetermined degree for supplying current at a higher voltage to said actuating motor.

2. The combination with a plurality of series connected electric motors, a power controller for said motors having power on and power off positions, a fluid compressor, and an electric motor for actuating said compressor, of means operated upon a fall in the pressure of the fluid compressed by said compressor to a predetermined degree when said controller is in a power on position to connect said actuating motor to the circuit including said series connected motors at a point intermediate two of said motors for supplying current at one voltage to said actuating motor, and means operated upon a fall in the pressure of fluid compressed by the compressor to a predetermined degree for supplying current at a higher voltage to said actuating motor.

3. The combination with a plurality of series connected electric motors, a power controller for said motors having power on and power ofi positions, a fluid compressor, and an electric motor for actuating. said compressor, of means operative when said controller is in a power on position and the pressure of the fluid compressed by said compressor is reduced to a predetermined degree, to connect said actuating motor to the circuit including said series connected motors at a point intermediate two of said motors for supplying current at one voltage to said actuating motor, and means operative to supply current at a higher voltage to said actuating motor when the pressure of the fluid compressed by said compressor is reduced to a predetermined pressure less than the pressure at which the first mentioned means operates to supply current to said actuating motor.

4. The combination with a plurality of series connected electric motors, a power controller for said motors having power on and power ofi positions, a fluid compressor, and an electric motor for actuating said compressor, of a compressor governor device including a switch adapted to connect said actuating motor to the circuit including said series connected motors at a point intermediate two of said motors for supplying current at one voltage to said actuating motor when said controller is in a power on position, said governor being operated by variations in the pressure of the fluid compressed by said compressor for opening and closing said switch, and an additional compressor governor device including a switch adapted to close a circuit to said actuating motor for supplying current at a higher voltage to said actuating motor upon a fall in the pressure of the fluid compressed by said compressor to a predetermined pressure less than the pressure at which the first mentioned governor device operates to close the. first mentioned switch.

5. The combination with a plurality of series connected electric motors, a power controller for said motors having power on and power off positions, a fluid compressor, and an electric motor for actuating said compressor, of a high pressure compressor governor including a switch adapted to connect said actuating motor to the circuit including said series connected motors at a point intermediate two of said motors, said ov rn r being operated upon a reduction. in the pressure of the. fluid compressed by said compressor to a predetermined degree to close said switch for supplying current at one voltage to said actuating motor when said controller is in a power on position, and a low pressure governor including switch means in series with said switch and also including other switch means, said low pressure governor being operative to maintain the first mentioned switch means in closed position and the second mentioned switch means in open position at a predetermined low pressure. of the fluid compressed by said compressor less than the pressure at which said high pressure governor operates to open the circuit to said actuating motor, said low pressure governor being also operative upon a reduction in the pressure of the fluid compressed by said compressor to a predetermined pressure less than the pressure at which said high pressure governor operates to open the circuit to said actuating motor, to move the sec ond mentioned switch means to closed position for closing a circuit for supplying current at a higher voltage to said actuating motor and to move the second mentioned switch means to open position for preventing current thus supplied to said actuating motor from flowing to said series connected motors.

6. In combination, a vehicle having a driving motor, a power controller for said motor having power on and power off positions, a compressor, a motor for driving said compressor, a first circuit for supplying current at one voltage to said compressor motor when the power controller is in the power on position, a second circuit for supplying current at a higher voltage to said compressor motor irrespective of the position of the power controller, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit.

7. In combination, a vehicle having a driving motor, a power controller for said motor having power on and power off positions, a compressor, a motor for driving said compressor, a first circuit for supplying current at one voltage to said compressor motor when the power controller is in the power on position, means responsive to the pressure of the fluid compressed by the compressor and controlling said circuit, a second circuit for supplying current at a higher voltage to said compressor motor irrespective of the position of thepower controller, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit.

8. In combination, a vehicle having a driving motor, a power controller for said motor having power on and power off positions, a compressor, a motor for driving said compressor, a first circuit for supplying current at one voltage to said compressor motor when the power controller is in the power on position, means responsive to the pressure of the fluid compressed by the compressor and controlling said circuit and operable on a reduction in the pressure of said fluid to a predetermined value to complete said circuit, a second circuit for supplying current at a higher voltage to said compressor motor irrespective of the position of the power controller, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit and operable on a reduction in the pressure of said fluid to a value lower than said predetermined value to complete said circuit.

9. In combination, a vehicle having a driving motor, a power controller for said motor having power on and power oiT positions, a compressor, a motor for driving said compressor, a first circuit for supplying current at one voltage to said compressor motor when the power controller is in the power on position, a second circuit for supplying current at a higher voltage to said compressor motor irrespective of the position of the power controller, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit and for interrupting said first circuit.

10. In combination with a vehicle having a driving motor, a power controller for said motor having power on and power off positions, a compressor, a motor for driving said compressor, a first circuit for supplying current to said compressor motor to effect operation of the compressor at one speed when the power controller is in the power on position, a second circuit for supplying current to said compressor motor irrespective of the position of the power controller to effect operation of the compressor at a higher speed, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit.

11. In combination with a vehicle having a driving motor, a power controller for said motor having power on and power ofi positions, a compressor, a motor for driving said compressor, a

first circuit for supplying current to said compressor motor to effect operation of the compressor at one speed when the power controller is in the power on position, means responsive to the pressure of the fluid compressed by the compressor and controlling said first circuit, a second circuit for supplying current to said compressor motor irrespective of the position of the power controller to effect operation of the compressor at a higher speed, and means responsive to the pressure of the fluid compressed by the compressor and controlling said second circuit.

12. The combination with a vehicle having a driving motor and a power controller for said motor having power on and power off positions, a compressor and a driving motor for said compressor, of means operative when said controller is in a power on position and the pressure of the fluid compressed by the compressor is reduced to a predetermined degree to supply current to the compressor motor to effect operation of the compressor motor at one speed, and means operable when said power controller is in the power off position and the pressure of the fluid compressed by the compressor is reduced to a pressure less than said predetermined degree to supply current to said compressor motor to effect operation of the compressor motor at a different speed.

13. The combination with a vehicle having a driving motor and a power controller for said motor having power on and power off positions, a compressor and a driving motor for said compressor, of means operative when said power controller is in the power on position and the pressure of the fluid compressed by the compressor is reduced to a predetermined degree to supply current to the compressor motor at one voltage, and means operable when said power controller is in the power oiT position and the pressure of the fluid compressed by the compressor is reduced to a pressure less than said predetermined degree to supply current to said compressor motor at a. different voltage.

JOSEPH C. McCUNE. 

